Typically, materials in high temperature applications require shields incorporating channels for cooling. These shields are usually metal and must be thin and lightweight. They present problems because of their thermal expansion and their limited access and application, e.g. in the case of transparent IR windows. Attempts to isopress and sinter transparent ceramic window followed by drilling cooling manifolds in the ceramic windows has resulted in limited hole geometry capability.
Thin laminated ceramic structures containing small holes (0.006") for wire accommodation are routinely prepared for the electronics industry. Such multilayer structures are typically 0.001" to 0.050" thick and are laminated sandwich fashion with metal circuit layers screened on several if not all layers. Photo resist, carbon or other material patterns may also be layered between ceramic layers and may then be burned out to leave voids, shapes, manifolds, etc. However, very large manifolds in thick layers cannot be prepared by this method as the hole integrity is lost during pressing and in addition burnout problems often result in delamination. To date the tape casting method of ceramic body preparations has been limited by thickness and the lack of three dimensional capability. Dry pressing and extrusion have been considered more favorable for thicknesses greater than an eighth of an inch.